1. Field of the Invention
The present teachings relate to scroll compressors for compressing fluids, such as a refrigerant, and such scroll compressors may be utilized, for example, in air conditioning systems and refrigerating systems.
2. Description of the Related Art
Japanese Laid-Open Patent Publication No. 5-312156 discloses a known scroll compressor. As shown in FIG. 6, the known scroll compressor includes a stationary scroll member 110 and a movable scroll member 120. The movable scroll member 120 moves in an orbital motion about the stationary scroll member 110. The stationary scroll member 110 has a volute wall 112 extending from a base plate 111, and the movable scroll member 120 has a volute wall 122 extending from a base plate 121. The scroll members 110, 120 are arranged in such a manner that the respective volute walls 112, 122 are proximally disposed with respect to each other and co-operate to compress a fluid. A plurality of compression chambers 114 are defined between the stationary scroll member 110 and the movable scroll member 120. As the movable scroll member 120 orbits with respect to the stationary scroll member 110, fluid is drawn into the compression chamber 114 and compressed as the compression chambers 114 shift toward the center of the scroll members 110 and 120, thereby reducing the space within the compression chambers 114.
In the known scroll compressor, a high pressure is generated in the compression chambers 114 as the fluid is compressed. The high pressure is exerted against the stationary scroll member 110 and the movable scroll member 120. The pressure in the compression chamber 114 becomes higher as the compression chamber 114 shifts from the outer periphery toward the center of the scroll members. As a result, as shown in exaggerated form in FIG. 6, the movable scroll member 120 will deform so that its central section bulges towards to the right, as shown in FIG. 6. Because the end face of the outer peripheral portion 113 of the movable scroll member 120 and the end face 123 of the stationary scroll member 110 will come into contact due to the deformation of the movable scroll member 120, friction will be generated between the movable scroll member 120 and the stationary scroll member 110. Therefore, power loss and seizing may be caused by this friction.
It is accordingly an object of the present teachings is to provide an improved scroll compressor.
Because the movable scroll member of the known scroll compressor will deform as the pressure of the fluid in the compression chamber is increased, the known scroll compressor is prone to power loss and seizing when the compression chamber is under high pressure. Consequently, such problems are preferably overcome by the present teachings.
In one aspect of the present teachings, a scroll compressor may include a stationary scroll member, a movable scroll member and a plurality of compression chambers defined between the two scroll members. As the pressure in the compression chambers increases, the movable scroll member will deform. Therefore, end portions of the base plates of the scroll members are arranged and constructed to avoid contact when the movable scroll member deforms. Thus, by designing the end portions according to the present teachings, power loss and seizures can be avoided, thereby improving compression efficiency.
The end portions preferably comprise a contact avoiding structure, in which at least one of the end portions of the base plates of the scroll members has a shape that will avoid contact with the end portion of the other scroll member when the movable scroll member deforms. Although the contact avoiding structure may be relatively simple, it is effective to prevent contact between the end portion of the stationary scroll member and the end portion of the movable scroll member during operation under high pressure.
Such scroll compressors may preferably compress carbon dioxide (CO2) as a refrigerant. The pressure difference of CO2 between its lower pressure and higher pressure may be, for example, more than 5 MPa (megapascal). That is, when the carbon dioxide is compressed, the compression chamber 114 will be subjected to a higher pressure than usual, and the movable scroll member 120 is likely to deform. However, even if the movable scroll member deforms, scroll compressors according to the present teachings can effectively prevent the movable scroll member 120 from contacting the stationary scroll member 110.
For example, the scroll compressors may preferably be utilized in air conditioning systems and in refrigerating systems. More preferably, the scroll compressors may be utilized in automobile air conditioning systems.